A conventional hand-held unit for transmitting and/or receiving is described in International Patent Publication No. 95/24746. The unit includes as case.
A hand-held unit for transmitting and/or receiving is already known from World Patent 95/24746. The device includes a case containing an electrical circuit, a listening device on one side of the case, an electrical reference potential surface on the other side of the case opposite the listening device and an antenna resonator element which is arranged approximately parallel to the reference potential surface and one end of which has an electrically conducting connection to the reference potential surface.
A radio apparatus according to the present invention has the advantage that the antenna element on the case of the radio apparatus can assume various positions. This makes it possible to improve the transmission and/or reception conditions by changing the position of the antenna element. When the antenna element functions as a directional antenna, harmful irradiation of the user""s head can be avoided. Due to the positioning of the antenna element on the second side of the case and the shielding by the shielding enclosure, the radiation direction in this case points away from the user""s head, resulting in a reduction of irradiation of electromagnetic energy into the user""s head. If the technical properties of this antenna element are no longer sufficient for the connection to the base station, the user has the option, by changing the position of the antenna element, of taking advantage of the better characteristics of an omnidirectional antenna the radiation of which is no longer limited by the shielding enclosure. However, as a result, the irradiation into the user""s head is increased to a level that is customary for mobile telecommunications devices in widespread use today.
The radio apparatus according to the present invention thus combines the two antenna concepts that are customary today. It offers the user the option of selecting the operating mode best suited to his application situation. In normal operation, the user can benefit from the advantages of the directional antenna with relatively low irradiation into the body; however, under poor transmission conditions, the user has the option of taking advantage of the better radiation characteristics of an omnidirectional monopole antenna standing away from the radio apparatus and consequently obtaining a better connection.
It is advantageous that the antenna element is integrated into a case part which is movably mounted on the second side of the case. In this manner, the antenna element is protected against external influences and damage. In addition, an appropriate design of the shape of the case part can make it possible to facilitate and improve the action of moving the antenna element for the user.
A further advantage is that the impedance of the antenna element can be transformed via various matching circuits which are assigned to different positions. In this manner, the different impedances occurring at different antenna element positions can be optimally matched to the input impedances of the continuing circuits, so that optimum antenna characteristics can be preserved despite different antenna element positions.
A further advantage is that the antenna element can be connected so as to be electrically conductive with a shielding enclosure surrounding the printed circuit board. This represents a particularly simple and inexpensive possibility for implementing a matching circuit.
It is advantageous that the antenna element includes a sliding contact which is in contact with an electrically conductive contact surface on the second side of the case as a function of the position of the antenna element, the contact surface having an electrically conducting connection to the shielding enclosure. A contacting can be easily manufactured in this manner. In addition, the sliding contact may or may not contact the contact surface depending on the position of the antenna element as the result of a suitable arrangement of the contact surface. It is thus possible to implement two different matching circuits in an extremely simple manner.
A further advantage is that the antenna element is movably and/or rotatably mounted in a plane which is essentially parallel to the printed circuit board. This makes it possible for the user to set the antenna element in a plurality of positions, thus making it possible for him always to set an antenna element position that is necessary for optimum transmission and/or reception conditions for many different angles of inclination of his radio apparatus. A rotatable and/or movable mounting of the antenna element also makes easy-to-manufacture contacting possible, for example, via the sliding contact. Thus, the rotatable mounting offers the advantage, for example, that the antenna element may be in a vertical position even if the radio apparatus is tilted in relation to the vertical and it may thus transmit and/or receive in the same polarization as customary base station antennas according, for example, to the GSM standard (Global System for Mobile Communications).
If, for example, vertical linear polarized waves are transmitted and/or received and the radio apparatus with the antenna element is inclined in relation to the vertical, transmission and/or reception losses occur in relation to base station antennas receiving and/or transmitting in the same polarization, as is the case, for example, with the GSM standard. With a suitable radio apparatus, according to the present invention, the antenna element can thus be placed in a position in which the polarization direction is matched to the base station antennas, resulting in reduced transmission and/or reception losses.
A solution that is easy to manufacture is obtained by having one axis of rotation of the antenna element pass through the terminal. In this manner, the mechanical stress of the terminal and of the preferably coaxial connection of the terminal to a transmission and/or reception circuit on the printed circuit board is kept low.